A toxic water ban has been lifted for hundreds of thousands of people living in northwestern Ohio.

Toledo Mayor D Michael Collins lifted the ban on Monday after the latest test samples revealed that the city's water supply was safe to consume.

More than 400,000 residents have been scrambling to find clean water to drink and bathe in since Saturday when tests at one treatment plant showed readings for microcystin above the standard for consumption.

More than 400,000 residents endured the ban for three days

Earlier on Monday, Mr Collins said he was leaving the ban in place after the latest test results came back "too close for comfort".

He later called off the toxic water advisory after additional tests indicated the algae-induced toxin contaminating Lake Erie had dissipated to safe levels.

Video:Mayor Declares Water Safe To Drink

Mr Collins said: "Our water is safe. Families can return to normal life."

Residents in Ohio's fourth-largest city had been advised not to use tap water for any purpose, including brushing their teeth or even washing dishes.

Officials even warned against boiling the water, saying it could increase the toxin's concentration.

Governor John Kasich declared a state of emergency at the weekend and mobilised Ohio's National Guard to distribute water to those impacted by the ban.

There have been no reports of anyone becoming sick from consuming the water.

Algae blooms during the summer have become more frequent and troublesome around the western end of the lake - the shallowest of the five Great Lakes.

The algae growth is fed by phosphorus, mainly from farm fertiliser runoff and sewage treatment plants, and leaves behind toxins that have contributed to oxygen-deprived dead zones where fish cannot survive.